Checked Exceptions in HyperLogLog Serialization

src/main/java/com/clearspring/analytics/stream/cardinality/HyperLogLog.java

@@ -16,16 +16,15 @@
 
 package com.clearspring.analytics.stream.cardinality;
 
-import com.clearspring.analytics.hash.MurmurHash;
-import com.clearspring.analytics.util.Bits;
-import com.clearspring.analytics.util.IBuilder;
-
-import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
-import java.io.DataInputStream;
 import java.io.DataOutputStream;
 import java.io.IOException;
 import java.io.Serializable;
+import java.nio.ByteBuffer;
+
+import com.clearspring.analytics.hash.MurmurHash;
+import com.clearspring.analytics.util.Bits;
+import com.clearspring.analytics.util.IBuilder;
 
 /**
  * Java implementation of HyperLogLog (HLL) algorithm from this paper:
@@ -200,19 +199,18 @@ public int sizeof()
     }
 
     @Override
-    public byte[] getBytes() throws IOException
+    public byte[] getBytes()
     {
-        ByteArrayOutputStream baos = new ByteArrayOutputStream();
-        DataOutputStream dos = new DataOutputStream(baos);
-
-        dos.writeInt(log2m);
-        dos.writeInt(registerSet.size * 4);
-        for (int x : registerSet.bits())
+    	ByteBuffer buffer = ByteBuffer.allocate(8 + registerSet.size * 4);
+    	buffer.putInt(log2m);
+    	buffer.putInt(registerSet.size * 4);
+
+    	for (int x : registerSet.bits())
         {
-            dos.writeInt(x);
+    		buffer.putInt(x);
         }
-
-        return baos.toByteArray();
+    	
+    	return buffer.array();
     }
 
     /** Add all the elements of the other set to this set.
@@ -278,14 +276,16 @@ public int sizeof()
             return RegisterSet.getBits(k) * 4;
         }
 
-        public static HyperLogLog build(byte[] bytes) throws IOException
+        public static HyperLogLog build(byte[] bytes)
         {
-            ByteArrayInputStream bais = new ByteArrayInputStream(bytes);
-            DataInputStream oi = new DataInputStream(bais);
-            int log2m = oi.readInt();
-            int size = oi.readInt();
+        	ByteBuffer buffer = ByteBuffer.wrap(bytes);
+        	int log2m = buffer.getInt();
+            int size = buffer.getInt();
+        	
             byte[] longArrayBytes = new byte[size];
-            oi.readFully(longArrayBytes);
+
+            buffer.get(longArrayBytes, 0, size);
+
             return new HyperLogLog(log2m, new RegisterSet((int) Math.pow(2, log2m), Bits.getBits(longArrayBytes)));
         }
     }

src/main/java/com/clearspring/analytics/util/Bits.java

@@ -16,22 +16,22 @@
 
 package com.clearspring.analytics.util;
 
-import java.io.ByteArrayInputStream;
-import java.io.DataInputStream;
-import java.io.IOException;
+import java.nio.ByteBuffer;
 
 public class Bits
 {
 
-    public static int[] getBits(byte[] mBytes) throws IOException
+    public static int[] getBits(byte[] mBytes)
     {
         int bitSize = mBytes.length / 4;
         int[] bits = new int[bitSize];
-        DataInputStream dis = new DataInputStream(new ByteArrayInputStream(mBytes));
+        ByteBuffer buffer = ByteBuffer.wrap(mBytes);
+
         for (int i = 0; i < bitSize; i++)
         {
-            bits[i] = dis.readInt();
+            bits[i] = buffer.getInt();
         }
+
         return bits;
     }